When I need to create a new server I've always chosen Centos mainly for it's compatibility with Red Hat which i consider the standard de-facto for the general purpose linux server.
Now the problem is that Red Hat 6 has been out for quite a while and there is no sign of the Centos 6 (event Centos 5.6 iso is still missing).
As in the need to create a new server what will you do? Stay whit the old Centos 5.5 or switch to the recently released Scientific Linux 6.0?
I looked on SL 6.0 website and they declare great attention to compatibility with RH, I've never tried it by myself so I just wanted someone's real life opinion.

3 Answers
3

Both projects, of course, are binary-compatible rebuilds from the source provided by Red Hat. The primary differences are in the development/build model.

CentOS only makes changes to remove Red Hat branding, or very occasionally as a last measure to get something to build. They aim to be bug-for-bug compatible with Red Hat Enterprise Linux.

Scientific Linux makes more customizations and additions, for example building OpenAFS packages. (They do keep the SRPMs for these separate, though.)

CentOS is a "community" distribution, but it's really built and maintained by a small (but active) group of volunteer developers in a closed manner. The lack of communication from this group is sometimes frustrating and I think a problem they need to solve. Scientific Linux is much more open in its development model, and it's a lot easier to see what's going on.

In my impression, Scientific Linux is a lot more likely to accept "get it working" hacks, and CentOS a bit more careful, even if it means delay — as in the case of the CentOS 6 release.

Both are in production use at a lot of serious institutions. I don't think the delay of the CentOS 6 release is a huge cause for concern — it's just the way things are. (I think prioritizing 5.6 was the right move, since that's blocking some security updates. The fact that that's not done yet is more worrying.) Hopefully after the actual work of getting the release out the door is done there can be some evaluation and maybe some changes made in communication of status. But I also think you won't go wrong deciding to use Scientific Linux now. They're basically interchangeable, after all, and it shouldn't be terribly painful to switch if you change your mind later.

If your system is on the front lines and is mission-critical for your business, buying a Red Hat Enterprise Linux subscription should also be on your list of options to consider. It's pricey, but not that pricey all considered, and by their nature CentOS and Scientific Linux always have some latency in getting security updates out the door.

Oracle Linux has the same close update repositories as Red Hat.
I have two kind of servers, mission critical and not. I usually use the least critical servers to try out the new features to be ready when I need to create a new mission critical machine (usually with a RH license), this is the main reason for wich I usually try out the latest RH clone available.
They usually aren't on the frontline.